The painting featured in the movie at the beginning is titled, "The Triumph of Death". It was painted by Pieter Brueghel the Elder, c. 1562, and is currently in the Museo del Prado in Madrid.
When shooting the scene where Paul interrogates Will, the boom operator had to sit in a tree for half the day to record the audio correctly.
Director Trey Edward Shults' simplest explanation of the film's title, which he spoke of at a screening in Chicago, is that the title came to him early on in the writing process before characters and plot were fully developed, and it stuck with him. He has also said it can represent the need to rest but at night, fear and anxiety can take over.
One of the pictures in the hallway is of Bill Withers, the singer famous for the hit song, "Lean on Me."
The film is shot mainly in 2.39:1, but the nightmare sequences are reserved in 2.75:1, however, in the climax, the film is shrunken all the way down to 3.00:1.